New Delhi: Iran's supreme leader Ayatollah Ali Khamenei has said that the country remains unbowed by pressure exerted by the United States and its "insults" against the Islamic republic, international news agencies reported.

Khamanei has said that Iran won’t give up over such insults, while making reference to US’latest sanction against him.

"The Iranian nation seeks dignity, independence and progress; that's why pressures by cruel enemies do not affect Iranians," Khamenei was quoted as saying in a speech to a crowd in Tehran, by AFP.

His office quoted him as saying “the graceful Iranian nation has been accused and insulted by the world's most vicious regime, the US, which is a source of wars, conflicts and plunder”.

His statements come after US President Donald Trump signed an executive order on Monday, imposing “hard-hitting" sanction on him . US sanctions on Iran could last 'years' and it will deny the Iranian Supreme Leader and other officials access to financial instruments within US jurisdiction, Trump has said.

Tehran and Washington have engaged in an escalating war of words following Iran's shooting down of a US drone last week.

The new measures are the latest against Tehran since Trump last year pulled out of a landmark nuclear accord between Iran and world powers.

"Imposing fruitless sanctions against Iran's supreme leader and the commander of Iran's diplomacy is the permanent closure of the path to diplomacy with Trump's desperate government," ministry spokesman Abbas Mousavi said in a tweet.